Tire cord application station and method

This invention relates generally to an improved apparatus for manufacturing a toroidal carcass ply for a tire and, more specifically, to an apparatus station and method for applying a cord ply to an annular tire building surface.

Historically, the pneumatic tire has been fabricated as a laminate structure of generally toroidal shape having beads, a tread, belt reinforcement, and a carcass. The tire is made of rubber, fabric, and steel. The manufacturing technologies employed for the most part involved assembling the many tire components from flat strips or sheets of material. Each component is placed on a building drum and cut to length such that the ends of the component meet or overlap creating a splice.

In the first stage of assembly the prior art carcass will normally include one or more plies, and a pair of sidewalls, a pair of apexes, an innerliner (for a tubeless tire), a pair of chafers and perhaps a pair of gum shoulder strips. Annular bead cores can be added during this first stage of tire building and the plies can be turned around the bead cores to form the ply turnups. Additional components may be used or even replace some of those mentioned above.

This intermediate article of manufacture would be cylindrically formed at this point in the first stage of assembly. The cylindrical carcass is then expanded into a toroidal shape after completion of the first stage of tire building. Reinforcing belts and the tread are added to this intermediate article during a second stage of tire manufacture, which can occur using the same building drum or work station.

This form of manufacturing a tire from flat components that are then formed toroidially limits the ability of the tire to be produced in a most uniform fashion. As a result, an improved method and apparatus has been proposed, the method involving applying an elastomeric layer on a toroidal surface and placing and stitching one or more cords in continuous lengths onto the elastomeric layer in predetermined cord paths. The method further includes dispensing the one or more cords from spools and guiding the cord in a predetermined path as the cord is being dispensed. Preferably, each cord, pre-coated with rubber or not so coated, is held against the elastomeric layer after the cord is placed and stitched and then indexing the cord path to a next circumferential location forming a loop end by reversing the direction of the cord and releasing the held cord after the loop end is formed and the cord path direction is reversed. Preferably, the indexing of the toroidal surface establishes the cord pitch uniformly in discrete angular spacing at specific diameters.

The above method is performed using an apparatus for forming an annular toroidially shaped cord reinforced ply which has a toroidal mandrel, a cord dispenser, a device to guide the dispensed cords along predetermined paths, a device to place an elastomeric layer on the toroidal mandrel, a device to stitch the cords onto the elastomeric layer, and a device to hold the cords while loop ends are formed. The device to stitch the cords onto the elastomeric layer includes a bi-directional tooling head mounted to a tooling arm. A pair of roller members is mounted side by side at a remote end of the tooling head and defining a cord exiting opening therebetween. The arm moves the head across the curvature of a tire carcass built on a drum or core while the cord is fed through the exit opening between the rollers. The rollers stitch the cord against the annular surface as the cord is laid back and forth across the surface, the first roller engaging the cord along a first directional path and the second roller engaging the cord in a reversed opposite second directional path.

The toroidal mandrel is preferably rotatable about its axis and a means for rotating is provided which permits the mandrel to index circumferentially as the cord is placed in a predetermined cord path. The guide device preferably includes a multi axis robotic computer controlled system and a ply mechanism to permit the cord path to follow the contour of the mandrel including the concave and convex profiles.

While working well, certain challenges exist in the aforementioned proposed apparatus and method. First, the tooling head rollers are configured and mounted to maintain continuous contact with the annular surface while each roller alternatively engages the cord along a respective application path. Such a configuration results in greater than preferred surface contact between the applicator head and the annular surface because both rollers are in constant contact with the surface. Constant contact between each roller and the annular surface requires that relatively more force is needed to move the roller head over the surface. Moreover, the mechanism required to move the applicator head along the curvature of a tire carcass and to form the loop ends of the cord at each terminal end of a carcass traverse is undesirably complicated because of the fixed angular relationship of both rollers to the annular carcass surface, resulting in increased tooling manufacturing and maintenance costs.

Also, while the apparatus and method described above represents a faster and more efficient technique for laying a cord ply on an annular surface, a need for even greater speed and efficiency remains. Producing a cord ply on a core by means of single cord application to the circumference of a core surface consumes significant manufacturing time. The cord laying operation, in fact, can represent the most significant time component in building a tire layer by layer on a core. Improvement in the cord application step in the process through increased speed and efficiency is, therefore, extremely important and valuable in achieving overall commercial validation of the process.

A need, accordingly, remains for an applicator head that is simple to construct, operationally reliable and efficient, and effective in bi-directional application of a single end cord to a tire carcass. Furthermore, a need exists for an applicator head that can effectively apply a tire cord without the need for separate equipment to form loop ends, and separate equipment necessary to press and release the cord. Additionally, a need exists for a station and method that can efficiently and quickly apply a cord ply to a core so as to minimize the time required.

Pursuant to one aspect of the invention, a ply application station for applying a tire carcass cord ply to an annular surface includes a plurality of applicator heads disposed at respective spaced apart circumferential locations about the annular surface, each applicator head proximally positioned to a respective assigned region of the annular surface. At least one ply cord is applied by each head on the annular surface region assigned respectively to each head. According to a further aspect of the invention, the plurality of applicator heads operate substantially in unison. The annular surface may be rotationally indexed a pre-determined angular distance to move the respective assigned surface region relative to each applicator head.

According to a further aspect of the invention, a cord engaging device preferably although not necessarily in the form of in-line rollers is mounted to reciprocally move in a forward and a reverse direction across the assigned annular surface region of each applicator head, the rollers positioning one or more cords on the assigned annular surface region of the applicator head in the forward and reverse directions. The rollers may be tilt in alternative directions in the forward and reverse directions to alternatively engage one or the other of the rollers against the annular surface.

In another aspect of the invention, a method for applying a tire carcass cord ply to an annular surface of a tire component includes: positioning a plurality of ply applicator heads at respective spaced apart circumferential locations about the annular surface, each applicator head proximally positioned to a respective assigned region of the annular surface; and coordinating operation of the plurality of applicator heads for respective application of at least one ply cord by each applicator head on the annular surface region assigned respectively to each applicator head. The applicator heads may operate in unison to substantially simultaneously apply the ply cord to all assigned surface regions in order to expedite the cord ply application step.

“Aspect Ratio” means the ratio of a tire\'s section height to its section width.

“Axial” and “axially” means the lines or directions that are parallel to the axis of rotation of the tire.

“Bead” or “Bead Core” means generally that part of the tire comprising an annular tensile member, the radially inner beads are associated with holding the tire to the rim being wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes or fillers, toe guards and chaffers.

“Belt Structure” or “Reinforcing Belts” means at least two annular layers or plies of parallel cords, woven or unwoven, underlying the tread, unanchored to the bead, and having both left and right cord angles in the range from 17° to 27° with respect to the equatorial plane of the tire.

“Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction.

“Carcass” means the tire structure apart from the belt structure, tread, undertread, over the plies, but including beads, if used, on any alternative rim attachment.